Salt lake brine electrodialysis tail liquid recovery method

Abstract

The invention discloses a salt lake brine electrodialysis tail liquid recovery method which comprises the following steps: electrodialysis tail liquid enters a continuous adsorption moving bed from an adsorption raw material pool so as to realize separation and extraction of lithium ions, and qualified liquid is obtained; the qualified liquid enters an ultrafiltration system, colloidal pollutants and suspended solids in the concentrated liquid are removed through the ultrafiltration system, and an ultrafiltration qualified liquid is obtained; the qualified ultrafiltration liquid enters an RO system to obtain an RO concentrated solution; the RO concentrated solution enters a sand filtration system to obtain sand filtration produced water, and the sand filtration produced water enters a sand filtration produced water tank; the sand filtration produced water enters a reverse osmosis system to obtain reverse osmosis produced water, and the reverse osmosis produced water enters a reverse osmosis produced water tank; concentrated water generated by the reverse osmosis system is recycled. The technical bottlenecks of low lithium recovery rate, serious membrane pollution and water resource waste in the traditional salt lake lithium extraction process are solved through four-step coupling of continuous adsorption, ultrafiltration, multi-stage RO and reverse osmosis recycling.

Description

Technical Field

[0001] The present invention belongs to the technical field of water treatment, and more specifically, relates to a method for recovering salt lake brine electrodialysis tail liquid. Background Art

[0002] With the continuous development of salt lake brine resource development technology, electrodialysis has been widely used as a key process for lithium extraction. However, the electrodialysis tail liquid still contains 0.6-0.8g / L of lithium ions and high concentrations of impurities (such as magnesium and boron). Traditional recovery processes have significant bottlenecks: First, the fixed-bed adsorption system suffers from low resin utilization and poor switching efficiency, resulting in a lithium recovery rate of less than 90%. Second, colloidal contaminants in the tail liquid easily cause membrane system fouling, and reverse osmosis membranes have poor operating stability under high pressure (>80bar), resulting in limited improvement in the total dissolved solids (TDS) of the concentrate. Third, the poor connection between the multi-stage process leads to low reuse of water for washing / analysis, making it difficult for the overall system yield to exceed 73%.

[0003] Related technologies using ion exchange resins for adsorption often face challenges such as long resin column switching cycles (>8 hours) and delayed adsorption saturation determination. In a cascade adsorption process, a single column residence time reaches 30 minutes, requiring over 120 hours for system stabilization. Furthermore, the lack of an integrated online conductivity monitoring valve position control system leads to significant fluctuations in the yield of the analytical solution (magnesium ion residual >2.0 g / L). Furthermore, flaws in the reverse osmosis system design mean that the freshwater reuse rate after secondary concentration is less than 60%, resulting in water waste.

[0004] In response to the above problems, how to achieve efficient lithium ion separation while breaking through membrane fouling limitations through ultrafiltration-reverse osmosis coupling design and building a water circulation system to improve resource utilization are key issues of concern to technicians in this field. Summary of the Invention

[0005] The purpose of this application is to provide a method for recovering salt lake brine electrodialysis tail liquid, which not only achieves efficient concentration and separation of lithium ions, but also breaks through the membrane fouling limitation through ultrafiltration-reverse osmosis coupling design, and constructs a water circulation system to improve resource utilization.

[0006] In view of the above defects or improvement needs of the prior art, the present invention provides a method for recovering salt lake brine electrodialysis tail liquid, comprising: The electrodialysis tail liquid is sent from the adsorption raw material pool to the continuous adsorption moving bed to separate and extract lithium ions to obtain qualified liquid; The qualified liquid enters the ultrafiltration system, and the ultrafiltration system removes colloidal pollutants and suspended solids in the concentrated liquid to obtain the ultrafiltration qualified liquid; The qualified ultrafiltration liquid enters the RO system to obtain RO concentrated liquid; The RO concentrate enters the sand filtration system to obtain sand filtration water, which then enters the sand filtration water production pool; The sand filtration produced water enters the reverse osmosis system to obtain reverse osmosis produced water, and then enters the reverse osmosis produced water pool; The concentrated water produced by the reverse osmosis system is recycled.

[0007] Optionally, the electrodialysis tail liquid is passed from the adsorption raw material pool to a continuous adsorption moving bed to separate and extract lithium ions to obtain a qualified liquid, including: The electrodialysis tail liquid passes through the adsorption zone, the water washing zone, the decomposition zone, and the top water zone in sequence, so as to separate and extract the lithium ions and obtain the qualified liquid.

[0008] Optionally, the qualified liquid enters an ultrafiltration system and the ultrafiltration system removes colloidal pollutants and suspended solids in the concentrated liquid to obtain the ultrafiltration qualified liquid, including: The qualified liquid enters the pretreatment system to obtain the ultrafiltration qualified liquid and ultrafiltration concentrated water; wherein the pretreatment system includes: a basket filter, a filter element filter, and an ultrafiltration membrane; The ultrafiltration concentrated water is recycled by using a multi-media filter.

[0009] Optionally, the ultrafiltration qualified liquid enters the RO system to obtain RO concentrated liquid, including: The qualified ultrafiltration liquid enters the first-level reverse osmosis membrane concentration system to obtain first-level fresh water and first-level concentrated water; The primary concentrated water enters the secondary reverse osmosis membrane concentration system to obtain secondary fresh water and concentrated liquid products; The primary fresh water and the secondary fresh water enter a three-stage reverse osmosis recovery system to obtain the third-stage fresh water and third-stage concentrated water; wherein the third-stage fresh water is RO concentrated liquid; The tertiary concentrated water enters the continuous separation system for recycling.

[0010] Optionally, also include: The concentrated liquid product enters the concentrated liquid product storage tank, passes through the basket filter, and then passes through the front end of the electrodialysis workshop for batching.

[0011] Optionally, the sand filtration produced water enters a reverse osmosis system to obtain reverse osmosis produced water, which then enters a reverse osmosis produced water pool, including: The sand filtration water passes through the filter and enters the pure water reverse osmosis system to obtain reverse osmosis fresh water and reverse osmosis concentrated water; The reverse osmosis concentrated water enters the concentrated water reverse osmosis recovery system to obtain the filtered water and discharged concentrated water, the discharged concentrated water enters the wastewater buffer tank, and the filtered water enters the filter water pool; The reverse osmosis fresh water is returned to the continuous ion exchange system analysis water pool for analysis water reuse The present application provides a method for recovering electrodialysis tail liquid from salt lake brine, comprising: the electrodialysis tail liquid is passed from an adsorption raw material pool into a continuous adsorption moving bed to achieve separation and extraction of lithium ions to obtain qualified liquid; the qualified liquid enters an ultrafiltration system, and the ultrafiltration system removes colloidal pollutants and suspended matter in the concentrated liquid to obtain ultrafiltration qualified liquid; the ultrafiltration qualified liquid enters an RO system to obtain RO concentrated liquid; the RO concentrated liquid enters a sand filtration system to obtain sand filtration water, and enters a sand filtration water production pool; the sand filtration water enters a reverse osmosis system to obtain reverse osmosis water, and enters a reverse osmosis water production pool; the concentrated water produced by the reverse osmosis system is recycled.

[0012] It has the following beneficial effects: By coupling continuous adsorption, ultrafiltration, multi-stage RO, and reverse osmosis reuse, the process overcomes the three major technical bottlenecks of traditional salt lake lithium extraction: low lithium recovery, severe membrane fouling, and water waste. This improves lithium recovery and reduces the membrane production cycle, addressing water resource constraints. Data from the examples demonstrates a total lithium recovery of ≥98%, a three-fold increase in membrane replacement cycles, and a 65% reduction in water consumption per ton of lithium produced, demonstrating significant industrial application value. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are merely embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on the provided drawings without any creative work.

[0014] Figure 1 A flow chart of a method for recovering salt lake brine electrodialysis tail liquid provided in an embodiment of the present application; Figure 2 This is a system block diagram of a salt lake brine electrodialysis tail liquid recovery method provided in an embodiment of the present application. DETAILED DESCRIPTION

[0015] The purpose of this application is to provide a method for recovering salt lake brine electrodialysis tail liquid, which not only achieves efficient concentration and separation of lithium ions, but also breaks through the membrane fouling limitation through ultrafiltration-reverse osmosis coupling design, and constructs a water circulation system to improve resource utilization.

[0016] In order to make the objectives, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only intended to illustrate the present invention and are not intended to limit the present invention. In addition, the technical features involved in the various embodiments of the present invention described below may be combined with each other as long as they do not conflict with each other.

[0017] The following is an example to illustrate a method for recovering salt lake brine electrodialysis tail liquid provided by the present application.

[0018] Please refer to Figure 1 , Figure 1 This is a flow chart of a method for recovering salt lake brine electrodialysis tail liquid provided in an embodiment of the present application.

[0019] Please refer to Figure 2 , Figure 2 This is a system block diagram of a salt lake brine electrodialysis tail liquid recovery method provided in an embodiment of the present application.

[0020] In this embodiment, the method may include: S101, the electrodialysis tail liquid is passed from the adsorption raw material pool to the continuous adsorption moving bed 10 to separate and extract lithium ions to obtain a qualified liquid; By utilizing the selective adsorption characteristics of aluminum-based adsorption resins for lithium ions and combining them with the dynamic adsorption-desorption cycle of a continuous moving bed, efficient separation of lithium ions can be achieved while avoiding the intermittent operation defects of traditional fixed beds.

[0021] This step may include: the electrodialysis tail liquid passes through an adsorption zone, a water washing zone, a decomposition zone, and a top water zone in sequence, so as to separate and extract lithium ions and obtain a qualified liquid.

[0022] The adsorption zone features a 6-in-parallel, 3-in-series configuration. Electrodialysis tail liquid is pumped from the adsorption feed pool (V-201) into six parallel resin columns, where it flows in three series groups (each group consists of two columns connected in series). The resin columns are loaded with aluminum-based adsorption resin, which selectively adsorbs lithium ions. The tail liquid (containing impurities such as magnesium and boron) is discharged into the tail liquid pool (V-202). When the outlet conductivity (112CT01) exceeds the set value, a valve (112VA02) switches to return the adsorption tail liquid to the tail liquid pool.

[0023] The water washing area is a three-column structure. Saturated resin columns enter the water washing area, where they are rinsed with qualified adsorption solution and tertiary concentrated water (from the water washing tank V-204) in a three-column series configuration. Residual brine is then pushed out to the adsorption raw material tank (V-201). This cleans impurities from the resin surface and prevents contamination of the desorption zone.

[0024] The desorption zone features a 2-in-parallel, 4-in-series configuration. After the resin columns enter the desorption zone, reverse osmosis product water and tertiary fresh water (from the desorption tank V-210) are pressurized by a pump and then flow through two parallel groups and four columns in series. The desorption water desorbs lithium ions adsorbed by the resin, and the high-concentration lithium solution (qualified solution) enters the qualified desorption solution tank (V-203). If the conductivity of the desorption solution exceeds the set value, it enters the qualified solution tank; otherwise, it returns to the water washing tank (V-204).

[0025] The top water zone is operated as a single column. The resin column is backwashed with the adsorption tail liquid, and the low conductivity water is returned to the desorption water tank (V-210), and the high conductivity liquid is discharged to the tail liquid tank (V-202).

[0026] As can be seen, in this step, the resin column automatically switches zones via a turntable, achieving 24-hour continuous adsorption and desorption, improving efficiency by over 30% compared to a fixed bed. Through multi-stage adsorption and temperature / conductivity control, lithium recovery rates of ≥90% are achieved. The water-washing zone reduces magnesium ion content to ≤1.8 g / L and boron ≤1.5 g / L, improving the purity of the qualified solution.

[0027] S102, the qualified liquid enters the ultrafiltration system, and the ultrafiltration system removes colloidal pollutants and suspended solids in the concentrated liquid to obtain the ultrafiltration qualified liquid; Based on S101, this step removes colloids, macromolecular organic matter and suspended particles in the qualified liquid through the physical screening effect of the ultrafiltration membrane, protecting the subsequent reverse osmosis membrane from contamination.

[0028] This step may include: qualified liquid enters the pretreatment system to obtain ultrafiltration qualified liquid, ultrafiltration backwash water, and concentrated water; wherein the pretreatment system includes: a basket filter, a security filter (filter cartridge filter), and an ultrafiltration membrane.

[0029] Among them, for the filter element type filter, the qualified liquid first passes through a 10μm filter element type filter to intercept large particles of impurities and reduce the load on the ultrafiltration membrane.

[0030] Among them, the ultrafiltration membrane can use a 50kDa cut-off molecular weight ultrafiltration membrane, the operating pressure is ≤3 bar, 352m 3 / h qualified liquid enters the membrane system. The turbidity of the water production side (qualified ultrafiltration liquid) is ≤0.5 NTU, and the colloid removal rate is >95%.

[0031] Furthermore, for the concentrated water recovery process, ultrafiltration backwash water and 20 m 3 / h concentrated water enters the multi-media filter (quartz sand and activated carbon), and is returned to the ultrafiltration feed end after recovery, and the system water recovery rate is increased to 98%.

[0032] This step can extend the life of the RO (Reverse Osmosis) membrane. Ultrafiltration pretreatment extends the RO membrane fouling cycle from 30 days to 90 days. Furthermore, it reduces operating costs. The multi-media filter recycles concentrated water, reducing wastewater treatment volume by 20%.

[0033] S103, the ultrafiltration qualified liquid enters the RO system 30 to obtain RO concentrated liquid; Based on S102, this step utilizes the gradient pressure separation of multi-stage reverse osmosis membranes to gradually concentrate lithium ions and recover fresh water, thereby achieving lithium enrichment and resource recycling.

[0034] This step may include: the qualified ultrafiltration liquid enters the primary reverse osmosis membrane concentration system to produce primary fresh water and primary concentrated water; the primary concentrated water enters the secondary reverse osmosis membrane concentration system to produce secondary fresh water and concentrated liquid products; the primary and secondary fresh water enter the secondary reverse osmosis water recovery system to produce tertiary fresh water and tertiary concentrated water; the tertiary concentrated water enters the continuous ion exchange system for recycling. The concentrated liquid product enters the concentrated liquid product storage tank, passes through the basket filter, and arrives at the front end of the electrodialysis workshop for batching.

[0035] The first-stage RO concentration process can achieve a high pressure of 40 bar. The qualified ultrafiltration solution enters the first-stage RO membrane system (774 membrane elements). The lithium concentration of the produced water (fresh water) is ≤0.1 g / L, and the lithium concentration of the concentrated water is increased to 1.2-1.5 g / L.

[0036] The secondary RO concentration system can achieve an ultra-high pressure of 80 bar. The primary concentrate enters the secondary RO system (168 high-pressure membrane elements), with a lithium concentration of ≤0.05 g / L and a final concentrate concentration of ≥3.0 g / L (meeting product standards).

[0037] Among them, fresh water recovery is the RO3 system (two-stage reverse osmosis water recovery system). The first-stage fresh water and the second-stage fresh water enter the RO3 system (264 membrane cores, 25 bar), and the water (282 m 3 / h) returns to the analysis / washing process, concentrated water (31 m 3 / h) back to the continuous separation system for treatment.

[0038] S104, the RO concentrate enters the sand filtration system to obtain sand filtration water, which enters the sand filtration water production pool; the sand filtration water enters the reverse osmosis system to obtain reverse osmosis water, which enters the reverse osmosis water production pool; the concentrated water produced by the reverse osmosis system is recycled.

[0039] Based on S103, this step uses a combination of sand filtration and reverse osmosis to achieve deep desalination, converting raw water into high-purity recycled water, thereby realizing closed-loop resource utilization.

[0040] This step may include: raw water enters the pretreatment system to obtain sand filtration water; wherein the pretreatment system is a sand filtration system; the sand filtration water enters the pure water reverse osmosis system through the filter to obtain reverse osmosis fresh water and reverse osmosis concentrated water; the reverse osmosis concentrated water enters the concentrated water reverse osmosis system to obtain filtered water and discharged concentrated water, the discharged concentrated water enters the wastewater buffer tank, and the filtered water enters the filtration pool; the reverse osmosis fresh water returns to the analytical water pool.

[0041] Among them, sand filtration pretreatment can include: the raw water passes through 6 multi-media sand filters (quartz sand and manganese sand) to remove residual suspended matter, and the turbidity of the produced water is ≤0.5 NTU.

[0042] The treatment process of pure water RO system may include: sand filtration water enters pure water RO membrane (2 independent systems, 150 m 3 / h / set), the produced water conductivity is ≤30μS / cm, which is used for analysis and water washing processes.

[0043] Among them, the concentrated water re-concentration can include: the concentrated water of the pure water RO system enters the concentrated water RO system (high-pressure membrane), the produced water returns to the filtration pool, and finally the concentrated water is discharged (lithium concentration ≤ 0.02 g / L).

[0044] In summary, this example, through the coupling of continuous adsorption, ultrafiltration, multi-stage RO, and reverse osmosis reuse, overcomes the three major technical bottlenecks of traditional salt lake lithium extraction processes: low lithium recovery, severe membrane fouling, and water waste. Data from this example demonstrates a total lithium recovery of ≥98%, a three-fold increase in membrane replacement cycles, and a 65% reduction in water consumption per ton of lithium produced, demonstrating significant industrial application value.

[0045] The technical solution provided in this application is described below through another specific method for recovering salt lake brine electrodialysis tail liquid.

[0046] In this embodiment, the method may include: Step 1: The electrodialysis tail liquid enters the adsorption raw material pool from the 4# old brine pool, and the raw material enters the continuous separation and exchange system (continuous adsorption moving bed 10) to separate and extract lithium ions. After obtaining high-purity qualified liquid, it enters the ultrafiltration system 20.

[0047] Step 2: remove the colloidal pollutants and suspended solids in the concentrate by ultrafiltration to obtain a dialyzed clarified liquid that enters the RO system 30. The concentrate enters the concentrated water buffer tank and the sand filtration system and returns to the front end of the ultrafiltration system 20.

[0048] In step 3, the concentrated liquid obtained by separation and concentration of the RO1 system enters the subsequent process RO2 system for secondary concentration to obtain RO2 concentrated liquid. The first-stage RO dilute liquid and the second-stage RO dilute liquid can be recycled and reused for analysis / washing water through the second-stage RO3 membrane system.

[0049] In step 4, the raw water enters the multi-media filtration and then enters the reverse osmosis system 40. The reverse osmosis dilute liquid is used for analytical water, and the concentrated liquid enters the RO concentrate tank for secondary concentration. The secondary concentrated dilute liquid enters the filtration pool next to the raw water pool and the concentrated liquid is discharged.

[0050] Among them, the adsorption system may include: The main function of the adsorption device is to pump the electrodialysis tail liquid into the continuous adsorption moving bed 10. After adsorption, elution, analysis, and top water treatment, the qualified liquid is stored in the analysis qualified liquid pool (V-203) as the raw material of the ultrafiltration system 20.

[0051] The main function of the continuous moving bed is to realize the automatic and efficient operation of the resin unit. The resin column small unit is placed on a turntable and switched by the rotation of the turntable. The material is controlled by the valve core valve position switching, and the continuous moving bed is divided into adsorption, desorption, elution, and material top water functional areas. When the resin column reaches the designated area, the corresponding process is executed.

[0052] The main function of the resin column is to load aluminum-based adsorption resin, provide a reasonable adsorption rate and filling volume, and cooperate with the continuous moving bed to complete the entire process of adsorption and lithium extraction.

[0053] The main functions of the resin distributor are: to reasonably distribute the brine and fresh water entering the resin column to improve the adsorption efficiency, and at the same time intercept the resin in the resin column to prevent losses caused by resin leakage.

[0054] Among them, the adsorption process may include: The adsorption zone has 6 columns in parallel and 3 in series, the desorption zone has 2 columns in parallel and 4 in series, the water washing zone has 3 columns, and the top loading zone has 1 column. The single column stays for 10 minutes, and the cycle is 6 hours. According to engineering experience, the entire system can reach a stable state within 72 hours.

[0055] Adsorption area: The electrodialysis tail liquid (adsorption raw liquid pool V-201) passes through the adsorption feed pump 112-142P01 and is transported to the cross-over adsorption area, 6 in parallel and 3 in series into the resin column, and the lithium ions in the feed liquid are adsorbed on the resin. The column liquid at valve positions 13#, 14#, 15#, and 18# is discharged to the adsorption tail liquid pool V-202, and then transported out of the workshop to the external tail liquid pool by the adsorption tail liquid pump 105P01A / B; the column liquid at valve positions 16# and 17# are combined and enter the lower port of valve position 19#, and the decomposition water in the resin column corresponding to valve position 19# is pushed out and returned to the decomposition water pool V-210. When the outlet conductivity (112CT01) is greater than the set value, the valve 112VA02 is switched to open and 112VA01 is closed, and the adsorption tail liquid returns to the tail liquid pool V-202.

[0056] Water washing area: The adsorption saturated resin column enters the water washing area from the adsorption area. RO water (water washing pool V-204) is transported to the ion exchange water washing area through the water washing pump 114P01. 3 strings enter the resin column and push the raw materials in the resin column out to the adsorption raw material pool V-201.

[0057] Desorption area: After water washing, the resin column enters the desorption area from the water washing area. The desorption water (desorption water pool V-210) passes through the water desorption pump 113-143P01, is transported to the plate heat exchanger and heated to 38°C (the process parameters are determined with the adsorbent manufacturer), and enters the continuous desorption area. 2 in parallel and 4 in series enter the resin column. The 22# and 23# lower valve positions are pressurized by the middle desorption pump to desorb the lithium ions adsorbed in the resin; the desorption liquid at the 26# valve position goes to the qualified liquid pool V-203, and the outlet of the 27 valve position is controlled by the time mode or conductivity mode. The liquid less than the set value enters the water washing pool V-204, and the liquid greater than the set value enters the desorption qualified liquid pool V-203.

[0058] Topwater area: The topwater area is located at valve position 19, with a single column bottom inlet and top outlet. If the conductivity CT01122 is low, valve 122VA01 will be opened to return the water to the desorption tank (V-210). If the conductivity is high, valve 122VA02 will be opened to discharge the water to the adsorption tail liquid tank (V-202).

[0059] Among them, UF (ultrafiltration water purification equipment) and RO concentration processes can include: Ultrafiltration pretreatment and multi-media filtration system: To ensure the stable operation of the spiral membrane, a pretreatment system is set up before the RO membrane system for the adsorption qualified liquid. The pretreatment system adopts a large flow (cartridge filter and ultrafiltration membrane) two-stage pretreatment method to remove insoluble impurities, meet the feed index requirements of the RO membrane, and ensure the stable operation of the membrane. The ultrafiltration backwash water and concentrated water are recovered using a multi-media filter to improve the yield.

[0060] Designed total ultrafiltration capacity: 352m 3 / h, water output 352m 3 / h enters the primary reverse osmosis system 40, and the cross-flow filtration is about 20m 3 After the concentrated water and backwash water enter the multi-media, they are returned to the ultrafiltration feed for re-filtration. The number of membrane units required for the ultrafiltration system 20 is 2, and the processing capacity of each unit is 176m 3 / h.

[0061] Each unit is equipped with 82 ultrafiltration membrane cores, and two units together have 164 membrane cores; the maximum design pressure of the ultrafiltration equipment is 3 bar.

[0062] First-stage reverse osmosis membrane concentration system RO1: The total amount of water entering the first-stage reverse osmosis membrane system is the water produced by the ultrafiltration membrane and the concentrated water returned by RO3. The total water volume is based on a maximum of 383m 3 / h, concentrated water volume 134m 3 / h enters the RO2 concentration system, with a fresh water volume of 249m 3 / h enters RO3 for recovery. Among them, the first-stage reverse osmosis system 40 requires 774 membrane cores, each membrane tube is filled with 6 membrane cores, and the maximum design pressure is 40 bar.

[0063] Secondary reverse osmosis membrane concentration system RO2: In order to increase the total TDS, a high-pressure reverse osmosis concentration system is added to RO1 to continue the concentration. The total amount of water entering the secondary reverse osmosis membrane system is RO1 concentrated water, and the total water volume is based on a maximum of 134m 3 / h, concentrated water volume 70m 3 / h enters the post-process treatment, the fresh water volume is 64m 3 / h enters RO3 for recovery. Among them, the secondary reverse osmosis system 40 requires 168 membrane cores, each membrane tube is filled with 6 membrane cores, and the maximum design pressure is 80 bar.

[0064] Secondary reverse osmosis RO3 water recovery system: The fresh water from the primary and secondary reverse osmosis contains a small amount of lithium and a certain amount of boron. In order to improve the yield and remove part of the boron, the reverse osmosis water recovery system RO3 is used for separation. The total water volume is 313m 3 / h, part of which is 31m3 of concentrated water containing lithium 3 / h returns to the first-stage reverse osmosis RO1 for treatment, and the other part is fresh water 282m 3 / h recycled water enters other processes. The second-stage RO3 system requires 264 membrane elements, with each membrane tube loaded with 6 membrane elements, and a maximum operating pressure of 25 bar.

[0065] Flushing and Cleaning System: The system's cleaning and recovery process includes periodic maintenance cleaning and contamination recovery cleaning. The cleaning system includes a cleaning tank, heat exchanger, cleaning pump, safety filter, valves, piping, and on-site instrumentation. All equipment is assembled on a single chassis, forming a single unit. The effective volume of the cleaning tank can accommodate two days' use. The cleaning equipment is equipped with two tanks and two cleaning pumps. The tanks are constructed of fiberglass and equipped with a heating system.

[0066] Among them, the reverse osmosis process can include: pure water system, mainly composed of three systems, pretreatment system, pure water RO system, concentrated water RO system, with a total designed water treatment capacity of 300m 3 / h.

[0067] Pretreatment System: Sand Filtration Production: Water from the pressure pump room (raw water tank) flows through sand filter inlet pumps P401A, B, and C (three pumps, two in service, one backup) and enters six sand filtration systems for filtration. The produced water is partially sent to the RO system and partially to sand filter tank V-206 (for backwashing). Sand filter backwash: Backwash water from sand filter tank V206 flows through sand filter backwash pumps P402A and B (two in service, one backup), then flows to backwash water collection tank T-401 and is delivered to the tail liquid tank via delivery pump P409.

[0068] Pure water system: Pure water RO production: Sand filtration water (400m 3 / h) through a heat exchanger, two-stage safety filters, and pure water high-pressure pumps P403A and B to pure water ROA and ROB. The produced water is sent to RO production tank V-206, and the concentrate is sent to RO concentrate tank T-402. Pure water RO flushing: RO production tank V-206 is pumped to the pure water RO via flushing pump P407. The flushing water is then sent to backwash water collection tank T-401 and delivered to the tailings tank via external pump P409.

[0069] Brine RO System: Brine RO production: Brine tank T-402 is fed to the brine RO membrane system via inlet pumps P404A and P404B, a primary safety filter, and high-pressure pump P405. Produced water is sent to the filtration tank in the pressure pump room, and brine is sent to the tailings tank. Brine RO flushing: RO production tank V-206 is fed to the brine RO system via flushing pump P407. Rinse water is then sent to backwash water collection tank T-401 and delivered to the tailings tank via external pump P409.

[0070] The various embodiments in this specification are described in a progressive manner, with each embodiment focusing on the differences from other embodiments. Reference can be made to the common and similar parts between the various embodiments. For the devices disclosed in the embodiments, since they correspond to the methods disclosed in the embodiments, the description is relatively simple, and the relevant parts can be referred to the method description.

[0071] Professionals may further appreciate that the units and algorithm steps of each example described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, computer software, or a combination of the two. In order to clearly illustrate the interchangeability of hardware and software, the above description has generally described the components and steps of each example according to their functions. Whether these functions are performed in hardware or software depends on the specific application and design constraints of the technical solution. Professionals and technicians may use different methods to implement the described functions for each specific application, but such implementation should not be considered beyond the scope of this application.

[0072] The steps of the methods or algorithms described in conjunction with the embodiments disclosed herein may be implemented directly using hardware, a software module executed by a processor, or a combination of the two. The software module may be placed in random access memory (RAM), internal memory, read-only memory (ROM), electrically programmable ROM, electrically erasable programmable ROM, registers, a hard disk, a removable disk, a CD-ROM, or any other form of storage medium known in the art.

[0073] The above is a detailed introduction to a salt lake brine electrodialysis tail liquid recovery method provided by the present application. Specific examples are used herein to illustrate the principles and implementation methods of the present application. The description of the above embodiments is only used to help understand the method and core ideas of the present application. It should be pointed out that for ordinary technicians in this technical field, without departing from the principles of the present application, several improvements and modifications can be made to the present application, and these improvements and modifications also fall within the scope of protection of the claims of the present application.

Claims

1. A method for recovering salt lake brine electrodialysis tail liquid, characterized in that: include: The electrodialysis tail liquid is sent from the adsorption raw material pool to the continuous adsorption moving bed to separate and extract lithium ions to obtain qualified liquid; The qualified liquid enters the ultrafiltration system, and the ultrafiltration system removes colloidal pollutants and suspended solids in the concentrated liquid to obtain the ultrafiltration qualified liquid; The qualified ultrafiltration liquid enters the RO system to obtain RO concentrated liquid; The RO concentrate enters the sand filtration system to obtain sand filtration water, which then enters the sand filtration water production pool; The sand filtration produced water enters the reverse osmosis system to obtain reverse osmosis produced water, and then enters the reverse osmosis produced water pool; The concentrated water produced by the reverse osmosis system is recycled.

2. The salt lake brine electrodialysis tail liquid recovery method according to claim 1, wherein The electrodialysis tail liquid is transported from the adsorption raw material pool to the continuous adsorption moving bed to separate and extract lithium ions, and obtain qualified liquid, including: The electrodialysis tail liquid passes through the adsorption zone, the water washing zone, the decomposition zone, and the top water zone in sequence, so as to separate and extract the lithium ions and obtain the qualified liquid.

3. The salt lake brine electrodialysis tail liquid recovery method according to claim 2, wherein The qualified liquid enters the ultrafiltration system, and the ultrafiltration system removes colloidal pollutants and suspended solids in the concentrated liquid to obtain the ultrafiltration qualified liquid, including: The qualified liquid enters the pretreatment system to obtain the ultrafiltration qualified liquid and ultrafiltration concentrated water; wherein the pretreatment system includes: a basket filter, a filter element filter, and an ultrafiltration membrane; The ultrafiltration concentrated water is recycled by using a multi-media filter.

4. The method for recovering salt lake brine electrodialysis tail liquid according to claim 3, wherein: The qualified ultrafiltration liquid enters the RO system to obtain RO concentrated liquid, including: The qualified ultrafiltration liquid enters the first-level reverse osmosis membrane concentration system to obtain first-level fresh water and first-level concentrated water; The primary concentrated water enters the secondary reverse osmosis membrane concentration system to obtain secondary fresh water and concentrated liquid products; The primary fresh water and the secondary fresh water enter a three-stage reverse osmosis recovery system to obtain the third-stage fresh water and third-stage concentrated water; wherein the third-stage fresh water is RO concentrated liquid; The tertiary concentrated water enters the continuous separation system for recycling.

5. The method for recovering salt lake brine electrodialysis tail liquid according to claim 4, wherein: Also includes: The concentrated liquid product enters the concentrated liquid product storage tank, passes through the basket filter, and then passes through the front end of the electrodialysis workshop for batching.

6. The method for recovering salt lake brine electrodialysis tail liquid according to claim 5, wherein: The sand filtration water enters the reverse osmosis system to obtain reverse osmosis water, and then enters the reverse osmosis water production pool, including: The sand filtration water passes through the filter and enters the pure water reverse osmosis system to obtain reverse osmosis fresh water and reverse osmosis concentrated water; The reverse osmosis concentrated water enters the concentrated water reverse osmosis recovery system to obtain the filtered water and discharged concentrated water, the discharged concentrated water enters the wastewater buffer tank, and the filtered water enters the filter water pool; The reverse osmosis fresh water is returned to the continuous ion exchange system analytical water pool for analytical water reuse.

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